Bug #11214
closedCannot Get Correct Binding from inside of C Method
Description
I am trying to get the arguments passed into a method using the binding. This is possible using pure Ruby:
class RubyBindingClass
def foo(arg = nil)
return binding
end
end
binding = RubyBindingClass.new.foo
puts binding.eval("self")
# => #<RubyBindingClass:0x007fdc5224f7f8>
puts binding.local_variables.inspect
# => [arg]
You can see that the #<RubyBindingClass:0x007fdc5224f7f8>
is returned as self and the local_variables
correctly reports that arg
is in scope. When we access the binding from a C method, we do not get the same information
# Thanks to Frederick Cheung for the code snippet
require 'inline' # $ gem install RubyInline
random_main_variable = 2
class CBindingClass
inline do |builder|
builder.include "<time.h>"
builder.c_raw <<-SRC, :arity => 1
VALUE foo(VALUE self, VALUE arg){
VALUE ret = rb_funcall(self, rb_intern("binding"), 0);
return ret;
}
SRC
end
end
binding = CBindingClass.new.foo(10)
puts binding.eval("self")
# => main
puts binding.local_variables.inspect
# => [:binding, :random_main_variable]
Here you can see that self is reported as main
and that local_variables
is returning variables from the main scope instead of from within the C method.
I originally stumbled upon this while trying to get access to arguments via TracePoint: http://stackoverflow.com/questions/30584454/get-method-arguments-using-rubys-tracepoint. Is this binding behavior intentional? Should it be possible to get programatic access to arguments passed into a C defined method?